1. Field Of The Invention
The field of the present invention relates generally to bar code scanning devices. More particularly, the field of the present invention relates to a modular, handheld or fixed scanner for reading an optical bar code by means of a scanning laser beam.
2. The Prior Art
Conventional point of sale (POS) bar code label readers in use today are of two general categories, fixed and handheld. Fixed scanners are typically mounted in a counter top and are typically used in supermarkets where there is a well established flow of goods along a predetermined item path from one location to another. An example of such a conventional fixed scanner is described in U.S. Pat. No. 4,939,355 and in references cited therein. The scan lines produced by such a scanner are directed generally to the package along its path. In addition, the scan lines are directed at many angles to facilitate reading the bar code label at any orientation. This category has the advantage of freeing the checker's hands to move the item past the scanner.
In the second category, the scanner is held in the hand of the checker or sales person. In this case, there may be no fixed flow of goods, but rather the labeled items may be located in different directions from the checker or sales person. For example, in many POS locations, a large counter is used and the goods may come from either end of the counter. In such applications, a handheld scanner is most useful because the scanner can be directed to the label wherever it appears. Such scanners are described in U.S. Pat. Nos. 4,760,248 and 4,825,057, for example. This type of scanner generally produces a single line scan pattern which is repeated several times a second. This scan line is generally horizontal but can be rotated and pointed by the operator to scan across all the bars of the bar code label.
In some POS applications, a fixed scanner is required because the flow of goods along an item path is well defined. At other times, a handheld scanner is required because the labeled items may be coming from different directions. There is therefore a need for a scanner which can perform the functions of a fixed scanner and also the functions of a handheld scanner. Such a scanner which could be rapidly and conveniently converted from functioning as a fixed scanner to functioning as a handheld scanner would be very useful in POS applications which have widely different needs and differing item paths.
It would also be extremely advantageous from a cost and efficiency perspective, if a single bar code scanner could be designed as a modular component of a scanning system. Such a scanning device, in a first module, would be employed for unrestricted, multidirectional handheld scanning of various items. The scanner could then be changed to a second configuration for accurate scanning from a fixed location with respect to a well defined item path. Ideally, the scanner should be freely and quickly interchangeable between modules without any down time for modification and without any adverse impact o scanning performance.